WP7 + WinForms

I need to write object which inside WP7 XNA project where Newtonsoft.Json.WindowsPhone.dll included from WinForms application.

I receive "Could not load file or assembly 'System.Runtime.Serialization, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' or one of its dependencies. The system cannot find the file specified."

When iam including "Newtonsoft.Json.dll" to WinForms application the Json ignoring Ignore attribute.